Hmm…why is that? The obvious explanation is that there are just too darned many products out there. Significant variations from region to region make things worse, and if you ever did manage to catalog everything, you’d have to start all over again because so much would have changed in the meantime. A web guide would need a staff of twenty full-timers to stay on top of it all. The best we can hope for, I believe, is the rise of some sort of crowd-sourced food wiki. There’s nothing out there yet I’m aware of that isn’t in a uselessly prototypical form. In the meantime, here are some suggestions for eaters who want to a do their own research.

• The Eat Well Guide is very easy to use and tries to point you towards local, sustainable, organic food resources in your area. I say “tries” because the search results for my area (Vancouver) were somewhat limited. Perhaps you’ll do better if you’re near a major American city. Local Harvest is a similar site that connects you with organic farms and farmers’ markets (again, mostly in the U.S.).

• Britain’s Ethical Consumer does actually have a food buyer’s guide with ratings for individual products, but naturally it isn’t all that helpful to us Norte Americanos.

• If you want to get your food politics consciousness-raising on, here are ten blogs worth watching. They provide the kind of background information that makes it much easier to make wise food choices.

• Many articles on food quote “non-profit” organizations and refer to studies to back up their claims, but not all non-profits and studies are created equal. To find out whether you’re dealing with a legitimate source or an industry front group, you need look no further than Sourcewatch.org.

• Phil Howard has created some handy charts, detailing corporate acquisitions of little mom-and-pop organic food companies. Not saying you should stop buying a particular brand just because it’s been acquired, but it’s good to know what’s going on in the market.

• Lastly, if you are a twitterer you will find many fine slow-food, real-food tweeps by searching #ProFood and #Slowfood and similar hashtags. Take advantage of the hivemind. Once you refine your ‘followed’ list, Twitter becomes a powerful information aggregator.

If all else fails, you can never go far wrong by just plugging the product or brand in question into Google and seeing what happens. And if even that fails, why not try avoiding processed mystery foods altogether? Rediscover the joy of cooking. Get to know your fruit and veg on a whole new level and frequent farmers markets where you can shake hands with the people who grew your food. It’s worth the trouble. Taking the time to learn more about your food and to cook more from scratch will make you healthier and happier. Guaranteed.

Update: This just popped up on Mashable. Worth checking out: 10 New Sites For Socially Responsible Shopping.